According to WHO statistics on blood safety, 80 percent of the world's population has access to 20 percent of the world's safe blood supply. However, more than 40 percent (13,000,000 units) of the blood supply in the developing world is not tested for the three major transfusion-transmissible infections: human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV). Transfusion of unsafe blood accounts for 8-16 million HBV infections, 2.3-4.7 million HCV infections and 80,000-160,000 HIV infections each year. If inexpensive, rapid, improved dipsticks with sensitivity comparable to EIA were developed for blood screening, it would greatly improve the safety of the blood supply in developing countries. The overall aim of the project is to develop a rapid and sensitive HBsAg (HBV) dipstick assay designated as the HBV Reflex diagnostic. The test can be used in developed countries under circumstances where an immediate result is required. For the developing countries, we propose that this test be integrated into a Triplex test (for HBV, HIV and HCV) and used as the initial step of pre-donation screening in high prevalence countries. The associated second step is to use the HBsAg Reflex diagnostic test in order to identify the agent responsible for the positive Triplex test result. The specific aims for phase II are: 1. Further test development including optimization of reagents and components, and developing a dry format system for the test. 2. Scale up of prototype dipstick production under Good Manufacturing Practice (Documentation/Validation) for development and field evaluation trials. 3. Field evaluation of the final HBsAg Reflex Diagnostic Test for FDA approval.